Nowadays, the use of digital modelling through multiple CAx systems becomes more and more unquestionable. It allows many benefits (3D, automations, simulations, etc.) in spite of the fact that those different systems are individually used and are relatively isolated (i.e. not interoperable) during the product design process. Then more enhancement of product development might be possible if the whole design expertises (and IT applications), could collaborate dynamically (i.e. interoperate) in a complete virtual and collaborative engineering platform. For instance, product definition could be therefore seen as the synthesis of multidisciplinary information defined and assessed with respect to both collaborative activity and individual domain of expertise. At the same time, PDM/PLM systems are developed in most of cases as product data vault (product data referential of a company with internal PDM or projects collaborative referential with collaborative engineering platform). Nevertheless, current PLM are not able to manage more than only files (and not data breakdown) and then are not yet efficient for CAx systems interoperability. The paper aims at giving some first concepts and software demonstrators in order to tackle the problem of interoperability in virtual engineering design. The proposal is based on the PPO data kernel: a dynamic data structure able to integrate and merge multidisciplinary product data breakdown and to exchange them with other CAx applications. Then the current PDM/PLM systems will be defined as one of the CAx systems which interoperate with the kernel to benefit of both PLM and CAx potential functionalities. A business case will be studied between the PPO product data kernel and the Windchill (from PTC vendor) PLM system. Some recommendations for future work are then discussed to present what could be a generic interoperable software platform.